The Empire of the Other
Well, as they say, turnabout is fair play, so, since Teramis has recently been inspired by me, then it's my turn to be inspired by her post:
In my academic work, I am constantly confronted by and struggle with this problem of Otherness, whether gender, race, culture, etc. and fantasy and science fiction are the literatures that have taught me (personally and politically) to embrace the Other and to respect and seek out Difference.
I think this is also what appeals to me about Cosmic Horror (Lovecraft's style of horror and also his fantasy). There is something truly frightening about a vast empire ruled by intelligences that we can not only not communicate with, but that whose psyches we could never understand even if we did communicate with them.
Alien means alien.
(Which by the way is why the alien in the first Alien film is truly alien, and the Aliens in the second film are not: because Ripley makes contact with the queen, and communicates to her.)
Radical Otherness is incommensurable. Shared ground is non-alien by definition. Galactic Empires, then, are predicated on the requirement that their members possess at least some kinds of similarity, and are thus not alien to each other.
I think a cosmopolitan Empire is certainly possible and maybe even likely when a large cross-section of intelligences are able to come to terms with each other, and you can look to David Brin's Uplift stories for examples, but you have to go to something like Stanislaw Lem's Solaris of Fred Hoyle's The Black Cloud for real otherness.
One of the finest examples of this is then end of Arthur C. Clarke's "Childhood's End" where the next step in human evolution is to become Other and is thus something to be both celebrated and feared. Ah, the sorrow/joy of life in the Universe.
This could be the start of a beautiful conversation.... :-)